

Enemy Within offers bonuses for fast movement in the form of “Meld” containers, which contain new resources and self-destruct after a set amount of turns.

In the original Enemy Unknown, playing it safe was almost always the best idea-there was rarely any problem with taking as many turns as you needed to flush out every enemy and kill them safely. The most critical new pieces are changes to the average mission that alter tactical considerations. The updates in Enemy Within are generally good enough to support that concept. By adding new components to the existing XCOM game, Enemy Within aligns itself with other strategy games, like Civilization V or Crusader Kings II, that have expansions that enhance things for the next playthrough. It deprioritizes the cookie-cutter story, allows for letting go of squaddies who get killed, and makes restarting an uncontroversial idea.

There has always been a tension in XCOM concerning how it should be considered and played: is it like an RPG, with characters and a single story that you should be able to finish at some point after you start? Or is it like a strategy game, where you start, learn, start over, learn more, and maybe finally win? Personally, I've always found the latter idea more satisfying. But the most important thing to know about Enemy Within is that it consists of several major additions to the main XCOM campaign instead of being an entirely new entity.
